Introduction

Maybe you just watched a film about Madagascar and met some lemurs jumping and running through the forest. Maybe you visited the zoo and saw gorillas grooming each other and eating leaves. Maybe you passed an elementary school and saw kids swinging on the monkey bars. Or maybe you just looked at your thumb as you picked up a carrot to eat it and thought “wow, that’s pretty cool I can pick things up like that!” In all these scenarios, you are contemplating what it means to be a primate.

Building on the Mammal Pattern

One of the important things to know as we ask “what makes a primate a primate” is that the primate characteristics we see are all built on mammal characteristics. All primates are mammals. This means that based on what we know about mammals, we can assume some basic things about how primates are put together, how they function, and what they do. Four kinds of mammals are pictured below so when you look at the table below about mammal characteristics, you will be able to look for those traits in these pictures.

Table of Mammal Characteristics

Hair to insulate, sweat glands to cool off, and are “warm-blooded” so unlike reptiles, they don’t have to be in a sunny spot to stay warm

Nutritional Efficiency

Eat and digest a lot to keep themselves going

A hard palate that divides chewing and breathing apparatus so they can eat and breathe at the same time, two sets of teeth over the lifetime and several different kinds of teeth for different functions

Locomotion and Posture

Move in many different ways

A variety of options when traveling through the environment and seeking food

Multiple, Developed Life Stages

Spread growth and development over a longer period

Four main stages:

In Utero

Infancy

Juvenile

Adult

Humans add Childhood between Infancy and Juvenile

Behavioral Flexibility

Change behavior to cope with changes in the environment

A better chance of using resources, surviving and reproducing due to larger brains

See Morbeck, Galloway and Zihlman's book The Evolving Female for more on what it means to be a mammal and how primates build on those mammal characteristics.

Skeletal Features Related to Teeth and Snout

Why? Primates rely less on their sense of smell and more on vision. Primates also have a reduced number of teeth as compared to other mammals.

Several types of teeth: incisors, canines, premolars, molars

Why? With different types of teeth, they can eat a variety of foods and process food efficiently. They have incisors for biting, canines for shearing and premolars and molars for crunching food into digestable packages.

Skeletal Features Related to Eyes and Ears

Forward facing eye orbits

Why? Primates have an increased emphasis on vision, so natural selection acted to position the eyes best for taking in the most visual stimuli.

Stereoscopic vision

Why? Stereoscopic vision means that the fields of vision provided by each eye overlap, resulting in what's called depth perception. This is extremely useful for forest-dwelling primates, as it lets them judge how far away the next branch is as they are moving from tree to tree.

Three bones of the middle ear housed in a skull outgrowth (the auditory or petrosal bulla)

Quercus macrocarpa (Bur Oak) Using your stereoscopic vision, you can see that some of the branches of the oak tree are closer than others. Without that depth perception, all the branches would look flat and equally far away from you. Image courtesy of the US Forest Service, St. Paul Field Office.

Skeletal Features Related to Arms and Legs

Clavicles (collarbones)

Why? Primates have very extensive shoulder motion because the clavicle provides the only bony link between the upper limb and the trunk.

Two separate bones in the forearm and lower leg

Why? Having two bones allows for better limb motion and more precise movements.

Nycticebus pygmaeus (Pygmy loris) This loris is descending a branch, taking advantage of the limb motion afforded by two bones in the primate forearm and lower leg.

Skeletal Features Related to Fingers and Toes

Nails instead of claws

Why? Nails allow primates to manipulate objects more easily.

Increased thumb mobility

Why? Again, related to manipulating objects. As you move across the primate order from lemurs and lorises to great apes, including humans, the thumb becomes more and more mobile

Grasping feet

Why? Primates have more big toe mobility for grasping and climbing. The only exception is humans (Homo sapiens). We have lost the grasping ability in our feet because our feet are designed to serve as a platform for walking

Why? Longer lives and longer life stages are good for increased growth, especially brain growth. Primates have larger brains for their body size than a lot of other mammals, and are born with brains that still need to develop quite a bit outside of the mother’s body. Primates also spend a lot of time learning skills and strategies for food gathering and survival from their mothers and others in their social groups.

Information on the Internet

Primate Info Net
A searchable database of primate information run by the University of Wisconsin

The Primates Topic Menu
Clearly organized information about the Order Primates with information pages, flash cards to review information and interactive crossword puzzles to test your new knowledge

Animal Diversity Web: Order Primates
A comprehensive site with information about primates as well as many images of primates, specimens (for example, photographs of primate skulls and jaws) and sounds made by primates.

Valley Zoo School Primate Research Results
Information on five kinds of primates as well as classification information and some primate links put together by a Canadian primary school. Also has teacher resources like a kid-friendly primate observation sheet on the school's home page.

Gombe Page
Several fun chimp and primate-themed quizzes along with video clips of Jane Goodall greeting an audience with chimp sounds and talking about the Gombe chimpanzees.

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